Vegetarians are less likely to get diabetes

It is not easy to prove that following a particular diet has a positive effect on your health. However, an analysis conducted in 2019 did come close. 

Researchers systematically sought out studies in which participants were initially asked about their diet before being subsequently monitored for up to 28 years. They identified nine such studies involving a total of over 300,000 participants. 

Being a vegetarian plus a healthy lifestyle is even better 
The risk of developing type 2 diabetes over time was around 20 per cent lower for those who adhered to a vegetarian diet when compared to participants who followed a mixed diet. The risk was even 30 per cent lower for people who ate a healthy vegetarian diet (consisting of vegetables, fruit, salads, wholemeal grains and nuts). 

The "dosage" also played a role: The greater the percentage of plant-based foods, the lower the likelihood of developing type 2 diabetes. 

Vegetarians tend to be slimmer 
Being overweight greatly increases the risk of type 2 diabetes. Since vegetarians tend to be slimmer on average, this also lowers their risk of getting diabetes. 

Individuals following a vegetarian diet and who were also slim had a 50 per cent lower risk of becoming diabetic. However, apart from a lower overall body weight, there are other reasons why a plant-based diet can help prevent diabetes. 

Insulin is more effective 
One of the effects of a plant-based diet is that it makes muscles more responsive to insulin, the hormone that lowers blood sugar. It also reduces inflammation in the body and can lower blood pressure. Taken together, all of these factors can have the effect of preventing diabetes. Source: Jama Internal Medicine